What frequency do I crossover subs

My speakers go down to 45hz and I've been told to crossover the subs at 60hz. That doesn't make any sense to me. I would think the crossover point would be between 40 and 50hz. Is there anyway to figure this out scientifically?
Due to way too many variables, there is no way to figure out on paper what is the optimum crossover point for subs in your room. I followed this method successfully: set the point at which my mains were rated -3db on the low end, dialed in phase and matching volume on sub, then adjusted crossover +/- using an SPL meter for smoothest integration. Not difficult, just time consuming.
As low as possible as Danny points out but I'd recommend setting volume by ear as the off the shelf SPL meters don't work well at low frequencies. A correctly integrated sub is the one that calls attention to it self, in most systems with a sub its always set too loud, IMHO

Best of luck

Making sense at 60 hz: Maybe....your speakers are rated at 45 but how many db down....3,6, 10 db? Some manufacturers stretch the lower reading.

Scientifically: Your ears are the best instruments. Imagine someone looking at a row of TV's and asking someone else which one looks the best. Even then, if you ask 5 people you might get 5 different answers.

Advice (but using "your" ears): Interpolate. Set the x/o around 60 and listen to the lower midrange. Remember it's not a brick wall at 60. The sub will be putting out 120 and 180 hz also, how much depends on the slope. Then try it at 30. Keep doing that at lesser amounts above and below 45 til you get a sound you like.

My guess is that you'll find the best spot somewhere around 30 to 40 but there are many variables. Might be a good idea to invest in a SPL meter (Radio Shack around $50) to help with the volume and phase settings but start with your ears first.
If, you are not comfortable with your ears or you just want to be sure, the simplest way as onemug mentioned is to get an spl meter, you'll need to run seperate frequencies at 40, 50, 60, even 70 and see where each frequency peaks in your room. If you indeed have dips in the 60 to 70hz range, it may be beneficial to cross at 60... 60 is a spot though that peaks in many rooms, my guy instict would be to cross more like 40... good luck, Tim
Make sense to cross-over at 80Hz. 60Hz will be still to low.
This will depend a lot on the slopes of your speakers and subs. And yes, I agree that an SPL meter would help here. They are not expensive. Can't speak to the quality of them, but there are even SPL meter apps for iPhone and Android.
Most all of the above, but if you are running sub woofers to augument the bass of 2 way speakers, not to relieve the mid-range drivers of some of the load created by doing the bass, try running the main speakers full range and rolling off the subs as low as possible. A SPL meter can help finding the ideal cross over point as well as positioning them to take advantage of, or minimize room nodes/nulls caused by placement of the speakers, subs and mains, as well as the listening position.

Just a WAG, but if your speakers are -3db at 45hz, and your subs have a 6db per octave cross over slope, I would agree with Timlub and try setting the cross over at 40hz or lower. But consider the location of the sub will have a lot of influence on your decisions, its not just the cross over.

This decision also depends on the listening room, the shape of the FR of your sub(s) vs. your main speakers in the lower frequencies, and whether you're using digital room correction ("DRC", like Audyssey, ARC, or similar).

Without any DRC:

It's very likely that your carefully located, single subwoofer will produce notably smoother bass than your main speakers. This is because you can place the sub close to a wall where reflections of low frequency, long wavelength signals (destructive interference) are minimized. If you are using a pair of subs, their output is almost surely much, much smoother in the bass because, while each sub will still have small FR irregularities, those irregularities are likely at different frequencies and will tend to average out to a very smooth summed response (vs bass from main speakers out on the floor). IME, this difference will usually be pretty dramatic.

In this case, cross the subs just high enough to allow the subs to handle response where the room does its worst damage. In an effectively treated room (bass busters, etc), I've found that this will generally be somewhere around 70 to 80 hz, although it's obviously dependent on the characteristics of your specific room. In an untreated room, the worst issues usually persist up to +/- 125ish hz. I'd suggest that you experiment with frequencies between 70 and 100 hertz and see what sounds best.

If you're using DRC, then it's a different story. IME, the software will effectively smooth bass response wherever the subs are placed and wherever they are crossed. In this case, you have a lot of flexibility and the choice will be more dependent on the specific qualities of your subwoofer(s) vs your main speakers. Try it at 50hz and try it at 80 hz and see which you prefer.

Good Luck

All really good info. I will add this though, the most inaccurate controls I've encountered are the x-over controls on subs. Often, the setting mark is nowhere near actual. Your ears and eyes (take notes), along with patience are most important.
Im intrigued by Marty's point about bass smoothness. My mains extend to about 20 Hz, but the smaller center and surrounds can't do that. How important are the center and surrounds in setting crossover? I use a Velodyne SMS-1 bass manager to control a pair of HGS-15s.

I set the initial level of all speakers to be equal with my RS SPL meter, but trim the subs 6-10 dB because they seem too loud -- I assume the meter is relatively insensitive to LF. I like the level of the subs to be such that you don't identify them as a source of sound.

I've tried 40, 60, and 80 Hz crossover settings in the Oppo 95 (analog) and Cary Cinema 11a (digital) menus. Maybe I should just standardize on 80 Hz.


If you're using the SMS-1 in auto mode, you're only scratching the surface of that unit's potential.

The SMS-1 will output FR <200hz to any video monitor. You could hook that up to get a visual take and see how it correlates with what you're hearing. You'll also see the FR thru the x-over point that you've chosen. If you tweak the parametric DRC settings and slope, phase, etc. (assuming that you haven't already done so) to achieve the flattest FR around that point, you'll hear a really seamless hand-off from the main speakers to the subs.

You should also manually adjust for smooth FR below that point. Unfortunately, Velodyne (IMHO) mangled the auto-correct software and the cumbersome manual set-up is really mandatory for best results.

Let your ears be the jugde. When it comes to subwoofer integration there are no absolutely right or wrong solution even with DRC. It is up to you to decide how your bass suppose to be sound. You have to play around with sub placement, crossover point, phase, delay to find you ”near perfect” setting. Just my 2cts

I confess to having used the SMS-1 auto mode, but I bought an articulated mic stand at a local music shop in anticipation of manual set up. I need to get to it. I think the SMS-1 sends video to the DVDO, so I should be able to use the small (30") TV to monitor adjustments. The SMS-1 sits on a shelf above the DVDO, so if it isn't already connected it should be easy to do.


The OP asked for a "scientific" approach - which I took to mean he wanted an alternative to set-up by ear. I described one such "scientific" approach; set for flat FR at the listening position. In the end, he may prefer the "tune by ear" approach that you recommend, but now he has a different approach for comparison purposes.

BTW, my experience is that the "scientific" approach has yielded vastly preferable results, but that may only indicate my own shortcomings at setting up a sub by ear.

Weirdly, the point nobody ever seems to make regards the fact that recorded music has vastly disperate bass levels. I stuck a "chicken head" knob (left over from a guitar amp) on the gain pot on the back of my REL sub so I can (easily) adjust the level by feel without moving the sub away from the wall..this adjustment is to make things sound better...sort of the point of this hobby. I don't have tone controls on my preamp (because they're simply not cool) and absolutely do not need them...ever...and the crossover point stays the same...but the REL gain knob is needed often for small adjustment, otherwise I'd be stuck with anemic bass on old LPs or my walls would crumble when a large bass level kicks in on any number of recordings.

I don't think that your point is lost on most people. Lots of records suck in lots of ways - including too much/too little bass. Some folks tweak their systems for each record, but I'm probably just too lazy for that. Like the chicken head idea, though.


PS Even when the record has issues, there's always the purists's question of whether you want to hear what's on the record or whether you want to "fix" what's on the record by tweaking the system.

Personally, I'm already there with systems that correct for the room. When they start selling the system that can adjust itself for the recording flaws, I'll be first on line to sign up.
PS Even when the record has issues, there's always the purists's question of whether you want to hear what's on the record or whether you want to "fix" what's on the record by tweaking the system.

Personally, I'm already there with systems that correct for the room. When they start selling the system that can adjust itself for the recording flaws, I'll be first on line to sign up.
Marty I agree and it does take a while to come to a happy medium with all recordings. What worked best for me was to never move the x-over up once I started to hear too much bass.

That being said no one mentioned phasing/timing. The last thing you want is to have the sub either be ahead or behind the music. With my Rel B3 I had to move closer or farther but only by a inch or 2 at a time. BTW I just used my ears. I tried test cds with single frequency selections. For me when I had that (what I thought was dialed in w/the cd) it was way too much bass with music.

Again you have to listen with your ears. When I first had everything dialed in with my Dyn C1's I had my x-over set at 38 hz. The C1's are rated at 45hz. Then I upgraded to the C1 Signatures. Found the Rel to sound better at 34 hz. Next I upgraded my Frey Ic to the Tyr2. Here we go again - I had to reset the Rel again and now I have it at 32 hz. There are some recordings that don't go below 60hz. Don't try to fix that. Sounds like a pretty low x-over point but to me ALL my recordings sound good and balanced.
I replaced all the knobs on my current fave guitar amp with Chicken Heads so I can see the settings instantly. I say Chicken Heads for everybody! It just makes sense.

I do agree with you that the scientific method or DRC does help getting to the goal faster but the final jugdment is still by ears.
I think chicken heads are science at its best.